Whether you’re thinking of upgrading your favorite bolt gun or building one from components, a chassis system offers a compelling combination of performance and versatility that’s difficult to get from a traditional stock.

Walk down the firing line of a Precision Rifle Series or a National Rifle League match to see how popular chassis have become. We spoke with a couple of nationally ranked Precision Rifle Series competitors to learn what benefits they offer, and which features matter most. Keith Baker and Dave Preston are two guys at the top of their game and both shoot chassis systems. We’ll be referring to them throughout the article. In the interest of full disclosure, both have relationships with chassis manufacturer Masterpiece Arms.

Baker is a recent chassis convert, having moved from a traditional stock just over a year ago. “There was a lot I couldn't get out of a chassis,” says Baker, “that I could get out of a traditional stock at that time.” But, he says advances in chassis made him reconsider and switch to a chassis this last season.

CHASSIS VS. STOCK

For those wondering how a chassis and a stock differ, basically, it’s in two ways. First, in a traditional stock, the trigger guard and magwell (or internal magazine) are a single, separate component called bottom metal that’s bolted to the action with the stock sandwiched between them. A chassis is an all-in-one assembly that combines a stock, magazine well, and trigger guard into a single component.

Side note, the word “stock” comes from the old English “stocc” which could be used to describe a tree trunk or a pillory… both of which invoke the idea of something wooden that forms a foundation or prevents movement.

Second, Chassis and stocks differ in their method of bedding the action. Organic or hand laid stocks generally benefit greatly from the use of bedding compound, while aluminum chassis

BEDDING

The interface between the action and a chassis is either an integral bedding surface, or a drop-in bedding block, in some cases. The aluminum bedding area is machined into a shallow V or a gentle radius that cradles the steel action in two long lines along its length. As the action screws are tightened, the action is pulled down into the V and held fast. This is a big benefit of installing a barreled action in a chassis is that it simple. Screw two bolts down, torque to spec, and head to the range. Changing actions? Same procedure. The drawback of a universal fit using a V-block appears when torqueing and action into the chassis. V-blocks can create a fulcrum point where the action body radius tapers at the tang, as evidenced by the tang diving, tip-down, when the rear action screw is tightened. The hotspot can deform some actions enough to cause bolt bind or other issues.

Another method is radius bedding. Instead of the action riding on two rails, radius bedding means the bedding block is cut to match the bottom radius of the action. The increased contact area improves stability on actions that are well-machined and adhere to their expected diameter specs. Bottom line: Radius bedding offers higher performance, while V-blocks are more forgiving of out of spec actions.

In a stock, the action generally sits on aluminum pillars that surround the action screws. Some people leave this as is, while others spread a hardening material such as Marine-Tex or Devcon beneath the action and in the recoil lug pocket so the final bedding surface conforms to every undulation in the action body. (Caveat; some composite stocks come cut for a specific action and don’t require bedding.) Bedding prevents any movement of the action in the stock and provides maximum repeatability and, therefore, accuracy. Even a chassis can be bedded, but bedded actions and stocks are wedded for life. Stock shooters swear by the practice, but chassis guys say the improvement in accuracy when bedding a chassis is imperceptible in PRS/NRL/professional sniper shooting disciplines.

IMPORTANT FEATURES

We’re painting with a broad brush when we say traditional stocks have lagged behind in the feature development department compared to the latest in chassis systems. But, there are few, if any, stocks that have the versatility of the chassis systems we’re looking at in this article. You might find a stock that approaches the feature set of a chassis, but it will be expensive and you’ll likely have to order it and wait months for delivery.

ADJUSTMENTS Look for buttstock adjustments that go beyond simple length of pull and comb height. Canting and height-adjustable buttplates allow fine tuning of fit, as does the ability to move the cheek riser fore and aft. Because chassis are made from aluminum extrusions, it’s easier to program a CNC machine to churn out parts with QD sling receptacles, accessory attachment points, dovetail rails, and intricately machined buttstocks with built-in adjustment systems. While these things are doable on a traditional stock, manufacturing stocks with these features is labor intensive and requires adding parts instead of just cutting metal away, and is therefore more expensive.

ATTACHMENTS Preston likes putting stuff on his rifle, so he likes how aluminum chassis have ample attachment points for accessories. Adding things like external weights, side plates, forend thumb rests, sling points, and even side-mounted barricade stops are all doable with M-Lok slots. Night vision bridges that screw into the forend provide a platform to hold down the front of the gun without touching the scope or barrel. Third, the longer forend allows a bipod to stay on the rifle when mounting a large diameter barricade, such as corrugated pipe, 55-gallon drum, or an upright tire, with a shooting bag. The longer forend lets you push the bipod out far enough that it won’t come in contact with the barricade while the rifle is bagged just ahead of the magwell. The benefit here is the time saved when transitioning from the top of a tube to the ground since you won’t give up time deploying the bipod.

BAG RIDER Baker says a solid bottomed buttstock or a full length bag rider is helpful when building a shooting position on the clock. The more material on the underside of the buttstock, the faster and more forgiving it is when stuffing a bag under the gun. Some chassis makers offer an optional, proprietary bag rider, others put M-Lok slots or threaded holes on the bottom of the buttstock to accommodate an aftermarket bag rider.

BARRICADE STOP The chassis should have some way to prevent pressure on the magazine while loading the rifle into a barricade. Some chassis have a magwell or edge at the rear of the forend, others require spending a few bucks to add one.

BORE HEIGHT That’s the distance between the bore line and the bottom of the forend. A barrel that’s closer to the point of support creates less of a fulcrum effect and makes it easier to control muzzle rise under recoil.

CANT INDICATOR A built-in bubble level that shows when the rifle is level from side to side. You might not be aware how far from level your rifle while shooting in an awkward position, and a canted rifle reduces accuracy.

CHAMFERED RECOIL LUG POCKET This allows the chassis to mate effectively with an action that doesn’t have a square corner at the intersection of the recoil lug and the action body.

DOVETAIL RAIL Preston says it’s essential to have an Arca-Swiss style rail running the length of the forend. The 1.5-inch wide Arca rail has overtaken picatinny rail as the go-to accessory attachment system for forend support accessories. The continuous, uninterrupted rail lets you quickly position a bipod or other rail-mounted support or stop anywhere along the length of the rail. And when shooting without a bipod, the broad, flat surface provides more stability than a rounded handguard.

FOLDING STOCK It’s a nice-to-have that makes it easier to travel with a gun and makes getting at the bore more convenient for cleaning or boresighting. But, hinges are expensive options that add $100 to $600 to the base price of a stock, depending on the model. Hinges were once thought of as a sloppy point of failure, though the hinges on all the chassis we tested lock up like bank vaults.

FOREND LENGTH The longer, the better. When shooting in a prone position, the further apart your grounded points of contact are, the more stability you have. And, spreading the front and rear points of support gives the shooter finer control over adjustment from the rear of the rifle.

GRIP These chassis take either AR grips, or a proprietary grip. Grips that can move further or closer to the trigger are great for fine tuning the LOP, and interchangeable grip panels fit different sized hands. Both Preston and Baker say a vertical grip is more comfortable and gives them more latitude when building shooting positions. Baker says a vertical grip allows him to drop his elbow lower than he could with a traditional stock and get another point of contact on a knee, bag, or whatever, without straining his wrist. The angles promote effective contact with the front of the grip while putting the trigger finger in place for a good 90 degree trigger press. A vertical grip also offers more control over the rifle when moving between shooting positions.

SPIGOT SLOT To extend the wheelbase of a chassis, some companies offer their own proprietary spigot that installs in the forend and offers a way to get your bipod a few inches further out.

THUMB REST The open-thumb grip is popular in precision shooting because some people feel it makes for a cleaner trigger break as well as allows faster access to the bolt knob. Thumb rests make this grip more comfortable, efficient and offers an index point for repeatability. Some chassis have machined-in recesses, others, like the MPA Matrix, have interchangeable shelves to refine your grip.

TRIGGER ADJUSTMENT PORTS: Slots or holes in the trigger guard for access to trigger adjustment screws.

WEIGHT SYSTEM Aside from a brake or minimizing bore height, another way to reduce muzzle rise is by adding a few pounds to the front of the gun. Some chassis makers offer internal weights that ride inside the barrel channel and external weights that attach to various points on the forend and buttstock. A combination of weights also lets you adjust the rifle’s balance point.

“At 15 pounds, I probably shot the lightest rifle in the PRS finale last year,” says Baker. “Going to a 18 to 22 pound chassis, the forgiveness is fantastic.” Reduced muzzle rise makes it easier to see your impacts, and seeing your impacts is critical in competition since you’re your own spotter. And, a gun that balances just forward of the mag well is well-mannered on barricades.

TESTING

We tested the effectiveness of the bedding systems in each chassis by shooting three sets of 5-round groups with each product using the same two barreled actions and recording group sizes for each setup. We loosened and retightened the action screws on the third set of each group to see if taking the action out of the stock had an impact on accuracy, and found this third group size was indistinguishable from the first two group sizes for all the systems. As a control, we also shot both barreled actions from a pillar bedded, rubber over-molded BDL stock from Hogue and found it printed 5-30% looser groups when compared to the tested chassis.

There are too many variables, at play to relate the groups we shot with the accuracy a given system can provide. Our group size testing tells us only two things. One, it confirms the bedding is holding the action adequately; two, it suggests how well we could fit the chassis to our body. We aren’t using the group sizes to rank these products.

We ran both actions with a Vortex Razor HD Gen 2 4.5-27x and a range of AICS-pattern magazines including AI, MDT, Accurate Mag and Magpul. Our barreled action testbeds were:

Products

JP Enterprises APAC (Advanced Precision Ambidextrous Chassis)

DESIGN The APAC’s key differentiator is its 2-inch tubular aluminum handguard. It’s machine checkered and offers plenty of real estate to manhandle the front of the gun on barricades without risking POI shift from pressing down on the barrel. As for flair, it’s limited to running handguard accessories that’ll mount up on JP’s proprietary MK III accessory attachment points. The APAC comes with a QD sling socket, a pic rail section, and a full-length, 12 o’clock pic rail. We mounted the QD up front and left the rails in the box. Though, anyone running a clip on for coyote or sniper duty will appreciated the optic rail.

The top of the handguard interferes with actions that have extended pic rails. We tried mounting an Ultimatum Deadline action and ran into this issue. Scopes with big ocular bells will require a taller mount to prevent the bell from contacting the top of the handguard.

Despite its modular forend, the APAC exhibits excellent rigidity and repeatability. A long, thick tang extends from the action area and it’s sandwiched by the handguard above and Arca rail below, which are both secured with a combination of 18 screws. JP recognizes that a V-block can stress an action at the tang and, accordingly, the APAC’s manual recommends 30-inch pounds of torque at the rear and 45-inch pounds up front to prevent bolt binding.

FEATURES The APAC comes standard with a folding buttstock. A side button releases the hinge, which locks up so tightly that it may as well not be hinged at all. The hinge is reversible, and with bolt handle channels on both sides, the rifle is truly ambidextrous.

The 15-inch Arca rail is the second longest, continuous rail in our test fleet and it provides a lot of adaptability. The APAC’s use of AR style grips gives you plenty of options; we installed Ergo’s TDX-0 ($41.50) grip which was a good fit.

PERFORMANCE As recoil management methods evolve, some shooters are shouldering the buttstock further inboard to get more meat behind the rifle. The APAC is designed with this idea in mind, as evidenced by its shorter LOP. Proning out behind the rifle, we could roll the buttpad out and the comb up and lock them in place quickly with the big locking wheels. Moving to a barricade, we liked how quickly we could shorten the stock’s LOP for a more medial shoulder position. The mag catch is stout and features a compound shoulder that pushes on the mag and helps stabilize it in the magwell. The beefy magwell prevents feeding issues when loading the rifle into a barricade.

Kinetic Research Group Whiskey 3 Competition

DESIGN Three aluminum components bolted up to form the chassis with polymer grip panels, polymer comb riser panel and a spigot slot to extend the forend support. The main section, or backbone as KRG calls it, is a single piece of aluminum that holds the radius bedded action and extends to the muzzle-end of the chassis. An aluminum forend attaches to the backbone from beneath with 6 screws. The underside of the backbone is a T-slot that holds an optional 0.75 pound forend weight. The Whiskey-3 accepts several KRG forends, but the comp chassis comes with KRG’s Arca forend that has an integral Arca dovetail rail.

The W-3 comes with two sets of grips panels to suite your hand size and the unique grip design allows you to choke up higher and closer to the bore axis than is possible with the other rigs in our buyer’s guide.

FEATURES Radius bedding provides more contact area between the chassis and the action and results in excellent action stability. Plus, a shortened tang contact area eliminates tang dive. Polymer comb riser for comfort in extreme temps and o-rings on the riser stanchions for quick return to selected height after removal. Cheek riser has six positions fore and aft. Seven quick-set LOP settings at ¼-inch intervals with novel locking adjustment. To add weight to the rear, KRG offers heavy straight and angled bag riders, along with a heavy LOP spacer. We added 2.6 pounds to the chassis with the channel weight, heavy angled bag rider, and heavy LOP spacer. Integral Arca rail plus spigot provides 14.5 inches of rail space.

Oddly, the W-3 doesn’t include any QD sling attachments for the forend. They have plates that attach to each side and the underside of the forend for $26, each. The buttstock comes with QD sling cups, one on each side.

PERFORMANCE Radius bedding works. Our Bighorn Origin and the W-3 mated like geese and produced the tightest shot groups of the tested chassis. Even the nasty Remington action stayed put well enough to print the second tightest groups. The rifle balances well and we appreciated the polymer riser plate and grip panels when shooting a match in 15F temps. We did miss having a barricade stop and had a couple of feeding issues while jamming the mag into a barricade edge. We’d splurge for the $36 KRG barricade stop and mount it just in front of the mag.

LIKE High grip provides excellent leverage to manage recoil; radius bedding worked well with all tested actions.DISLIKE Lack of integral barricade stop or QD cups on forend.

Magpul Pro 700 **Editor's Choice for Best Value**

DESIGN Magpul caught a lot of $h|t early on with the Pro 700 by meatheads that thought it was an all polymer chassis. IRL, the Pro 700 has a strong and rigid, full length, aluminum skeleton beneath a bunch of carefully fitted polymer panels that make the chassis friendlier when handling it in the heat and cold. We pulled the poly panels off the chassis and were impressed with how well they fit. There are no gaps or flexy areas that might otherwise make the chassis feel cheap.

It uses a V-block for bedding and features three integral M-Lok attachment panels on the base and sides of the forend. Later production versions have a scallop on the leading edge of the recoil lug pocket to improve seating of actions with a chamfered recoil lug joint. The Pro 700 was one of the first chassis with a sliding grip and an integral thumb shelf. With a choice of two included, interchangeable grip panels, the Pro 700 accommodates a wide range of hands and grip styles.

FEATURES The M-Lok slabs make the Pro 700 supremely adaptable. Magpul’s offers several M-Lok-able Arca dovetail rails to bolt under the forend. For max adaptability, the full length version has M-Lok slots at the front end for full meta points. The back end of the rail captures the front action screw and the sliding grip captures the rear action screw. This might seem frivolous, but if you move a barreled action between the Pro 700 and a lightweight hunting stock for deer season, you’ll appreciate not wondering where the eff-ing screws got to.

The hinge on the folding version is strong, wobble-free and reversible. Swap the hinge and the move the bolt handle slot filler from one side to the other to suit lefthandidness without compromise. We also like the magwell and its low-profile but effective barricade stop that prevents mag bind when loading on a barricade. On the backend, while there’s an M-Lok field on the bottom of the stock, the long, flat base of the stock is a fine bag-rider on its own. We were bummed Magpul doesn’t offer a weight system until we realized we could just bolt on MDT’s M-Lok forend weights.

PERFORMANCE We used the Pro 700 for several club PRS matches and found it was comfortable, versatile, and accurate. Our Accurate Mag, AI, MDT, and Magpul mags all fit and fed 6.5 CM and 308 Win without any extra TLC. The tall forend isn’t great for managing recoil, but adding four MDT weights added a couple pounds and calmed the front end considerably. We noticed tang dive as the action is torqued into the chassis, so a dab of bedding compound under the tang may tighten groups up a hair. After shooting all the chassis in our test group over the course of a year, coming back to the Pro 700 felt like settling deep into the couch in our parent’s basement.

LIKE It’s got everything we need and the price is right. Without the folder, the Pro 700 is the least expensive chassis in our roundup; add the folder and it’s the same price as the non-folders in the group. Sliding grip and comfy thumbshelf are great features.DISLIKE Forend height is tallest of the test group.

DESIGN A monolithic aluminum design from the muzzle end to the buttstock interface, the ACC has no risk of play developing between the forend and the chassis body. A shallow V bedding block accommodates a wide range of R700 footprint actions, and the ACC is available for other actions as noted. It takes AR grips, but MDT’s optional $49 vertical grip offers fore/aft adjustment for fine tuning your trigger finger placement and is contoured to match the ACC’s thumb shelf ergonomics.

FEATURES Adding weight to a chassis to battle recoil isn’t a new thing, but when MDT released the ACC in 2018, the company refined the practice by allowing shooters to really customize the amount and placement of that weight. Up to five, 1/2-pound barrel channel weights slide under the barrel and screw securely into place from below. Someone at MDT was locked-on when they designed the channel weights because they can be installed and adjusted with the barreled action installed, plus they don’t impede the use of the forend’s bottom M-Lok slots. There’s slots for five more 0.6-pound, exterior M-Lok weights on the side of the forend, each with a bonus QD cup. Going all-in puts 8.6 pounds of muzzle rise resistance on the forend. To balance things out, add the ACC 0.65-pound buttstock weight and 0.44-pound steel bag rider.

If you don’t have an Arca compatible bipod, the underside of the forend has M-Lok slots, as well as a slight recess for the application of grip tape that helps the rifle stick to bags and barricades. The recessed tape doesn’t interfere with anything sliding along the rail. And, at 17.5 inches, that rail presents the most versatility of the test group. Chunky serrations on the magwell corners mean business when loading into barricades and it’s smartly scalloped for tip-up mag insertion when space is tight under the rifle.

PERFORMANCE Tang dive was evident with the ACC with all tested actions. Not enough to cause the bolt to bind, but as on the Pro 700, we might put a drop of bedding compound under it to ease tension on the action. Shot groups suggest the bedding works extremely well with factory and custom actions, alike. Nothing says call-your-shot like a 22 pound 6.5 Creedmoor prone on a bipod, but balancing the weight distribution means the gun also stays neutral balanced on a barricade bag. Just make sure you eat your Wheaties if there’s an off-hand stage in the match book.

DESIGN The BA is the OG of competition-specific chassis. And, it’s got everything a PRS guy might need baked right in. It’s based around a V-block bedding system that eliminates tang dive by moving the rear action contact point as far back as possible. The BA accepts AR grips, but it arrived with MPA’s Enhanced Vertical AR grip that also features a right-side thumb shelf and knuckle standoff supports a 90 degree angle for clean trigger pulls. The BA’s backbone is a single, long aluminum extrusions bolted to the buttstock assembly, with a machined thumb shelf that mates perfectly with MPA’s vertical grip. It includes 11 inches of Arca rail, plus a spigot that adds an additional 3.5.

FEATURES The BA includes just about every feature you might see on a competition chassis. The highlights, though are MPA’s signature moveable barricade stop, open-front and beveled magwell, huge slots in the trigger guard for access to trigger adjustment screws, and the unique Ultra Bag Rider with its shallow hand hook and tubular extension that speeds up bag placement by providing something to pinch with your bag hand fingers as you set the bag height. LOP and comb height adjustments are held by a detent and can be locked with an Allen wrench. The included spigot is reversible for use with dovetail or pic rail mounted accessories. The oblong holes in the chassis might look like M-Lok at a glance, but they aren’t. There’s no M-Lok on the BA. But, it does include a 2-round match saver that plugs into the magwell.

PERFORMANCE The BA’s grip, canting stock pad, lightly padded comb, the bag rider, and extended bipod reach make proning out a pleasure. Mag changes are smooth after adapting to the cutout in the front of the magwell and learning to index the mag from the front. On barricade, we dumped the bag and loaded into the square edge of wood using the BA’s included, rotating, moveable stop. It works, but we found loading downward on a barricade bag gave us better recoil management, in general. We pulled the pic rail from the night vision bridge to make it more comfortable to push down on, but it’s too far out in front to reach. We’d opt for the BA’s channel weights to reduce recoil.

LIKE So many smart features and included accessories, bag rider design, integrated vertical grip with thumb shelf.DISLIKE Proprietary accessory attachment points — bring the M-Lok!

Masterpiece Arms Matrix **Editor's Pick**

DESIGN The newest chassis in the group. The Matrix earns its name by offering a dizzying array of possible configurations based on the system’s 5 grip sizes, 3 thumb shelf options, and 4 trigger finger support sizes. The basic shape and construction of the forend, bedding area, and magwell are similar to the BA, it’s just a longer forend with M-Lok slots that work even with the barrel channel weight installed. Out back, there’s a hybrid grip that’s a little reminiscent of a highly vertical traditional/thumbhole stock with an added thumb shelf and a novel trigger finger support. The buttstock is substantial with a hollow space to insert a weight. The trigger port is positioned pretty far forward, placing the housings of our Timney, Triggertech, and X-Treme triggers all the way at the front of the inlet with very tight clearance.

FEATURES The Matrix’s grip system is unrivaled in the chassis market. It offers 60 grip/thumb shelf/finger support combinations, so we’re sure you can find something that works. We did, and it’s the standard setup. The grips differ in girth and angle, and thmb shelves offer a few different angles, and the finger supports put your knuckle at the right distance from the trigger for a 90 degree break. The grip system put our hand closer to the bolt handle, and sped up split times. No question, this grip system is slick. The weight system is three components. Up front two weights sit in the barrel channel and are held by screws from the outside, and the rear weight is a tube that slips into the buttstock and is held with a screw.

PERFORMANCE We aren’t sure how many of the 60 grip combos we tried, but it was at least 20 before we locked things in and headed to a club match. Recoil control is excellent, as we could load the gun from the rear while pulling in on the stock hook and adding a little downward pressure from the thumb, all without fear of influencing the trigger press thanks to that trigger finger support. The only issue that cropped up was a failure to feed, and that was our fault because we didn’t notice the rifle came with MPA’s adjustable mag catch. Once snugged up, all was good. Solid groups indicate effective bedding, and there’s no tang dive during installation.

LIKE Grip/thumb shelf options; finger support is more helpful than we thought; includes adjustable mag catch; M-Lok on handguard, sling cup on the base of the forend is helpful when loading on a tripod.DISLIKE Would like more weight options to tune the balance point.

Q LLC Side Chick

DESIGN Know that feeling when you pick something up that you expect to weigh something, but it doesn’t and you almost throw it in the air? That’s what picking up a bare Side Chick chassis is like. The thing is 2.5 pounds. That’s about the weight of a carbon fiber stock with barely any of the Side Chick’s extra skills. We’re stretching the definition by calling the Side Chick a competition chassis, but in the right hands, this thing will do the deed. This girl is a waif, but the M-Lok slots up front will accept MDT’s forend weights and turn her into more of a BBW if you need to rely on a mechanical aid instead of the tools God endowed you with, if you know what we mean.

At first blush, she looks like her components are a straight port from Q’s The Fix rifle. But, changes had to be made to accommodate a Remington 700 action. The handguard is same, but the center section is extended, the receiver is replaced with a V-block bedding area, an AICS-friendly mag catch is on the trigger guard and the grip is attached to the chassis with an glass-filled nylon adapter (the blue part.) And, the lines on the buttstock changed to fit over the R700 bolt handle when it’s folded.

FEATURES M-Lok up front, AICS mags in the middle, and threading for a mystery bag rider in the back. Up top, the Side Chick replaces the stock optic mount with its own 0 degree rail that ingeniously bridges the action to the chassis through the handguard for increased rigidity. The downside of this arrangement is that it only works with actions that use the original R700 scope base screw pattern, and that sidelines some premium actions, like the Bighorns and Ultimatum we have on hand. But, there are plenty of custom actions using the original scope base mounting pattern… and that's in addition to the 7.5 million stock R700s in the wild, so we’re not crying for Q; they’ll do fine.

PERFORMANCE With a couple of MDT’s external weights hanging on the handguard and 10 inches of Arca bolted to the bottom, the rifle balanced nicely just in front of the magwell. Groups from the .308 were on par with those shot from the other chassis and better than we got from the pillar-bedded Houge stock from which it came. There’s plenty of adjustment to fit the Side Chick, despite it’s anorexic appearance. Accurate and MDT mags ran fine, Magpul and AI mags interrupted bolt travel when resting on the mag.

LIKE Versatile enough to serve as a comp chassis and light enough to be a hunting stock.DISLIKE Compatibility limited to actions with original Remington 700 optic mount screw layout.